In recent years, photosemiconductor devices such as a light emitting element like a light emitting diode (LED) or the like that is put to practical use for various display boards, light sources for image reading, traffic signals, units for a large size display and so on, and a light receiving element and the like have been produced for the most part by using sealing resins. Epoxy resins are generally used as such resins for sealing because of being excellent in heat resistance, adhesive properties, humidity resistance, mechanical strength, electrical properties, and so on.
In the past, bisphenol based diglycidyl ethers and phenol based novolac type epoxy resins have generally been used as a sealing material (see, for example, Patent Literature 1). However, the case where a nitride based LED having a light emitting wavelength in the range from blue color to near infrared region that has been put to practical use in recent years is sealed by these conventional epoxy resins causes a problem that an aromatic ring in the epoxy resin absorbs short wavelength light thereby causing a yellowing and the emission intensity of the LED decreases remarkably.
By the way, in the past, it has been known that tetrahydroindene is generated as a by-product in synthesizing vinyl norbornene by the reaction of cyclopentadiene with 1,3-butadiene. And in recent years, an effective utilization method of this tetrahydroindene has been needed.
In Patent literature 2, for example, a method for producing a diepoxide of tetrahydroindene that is an epoxy compound having two cycloaliphatic skeletons within the molecule from tetrahydroindene is disclosed.
In Patent Literature 3, using a thermosetting resin composition, as a substitute for a glass substrate, prepared by blending (A) a non-ester type alicyclic epoxy compound, (B) an epoxy compound that is different from the above (A), and (C) a cationic polymerization initiator by a prescribed amount is disclosed, and a diepoxide of tetrahydroindene is illustrated as an example as (A) a non-ester type aliphatic epoxy compound.